Evaluation of a vascularized, self-healing structure fabricated via material extrusion

Material extrusion is a versatile 3D-printing platform for building complex one-off designs. However, the mechanical properties of parts printed using material extrusion are limited by the weak bonding between successive layers of the print, causing premature failure at these critical locations. In this work, an additively manufactured component is crafted which incorporates internal vascular channels capable of autonomously delivering a one-part healing agent to the site of interlaminar damage, when and where it occurs thereby restoring the base structure. The effectiveness of fracture toughness restoration was investigated for various healing times and healing agents. Healing efficiencies of greater than 100% are reported for experimental-type samples using acetone as the healing agent while control specimens using a non-solvent agent demonstrated no recovery. Fractography of damaged surfaces via optical imaging and scanning electron microscopy revealed multiple healing mechanisms that are discussed herein. Lastly, biological analogies and the viability of our design in application are discussed.